Bob Silvia pulled into the driveway of a wood-shingled Melrose home last week, and his eyes immediately darted toward the roof. He noted the barn-like slope, the snow pooled in the center, and finally the lip, swollen with ice, all the obvious signs of a bruising winter. The 51-year-old insurance adjuster, who has walked through homes wracked by tornadoes, hurricanes, and fires, entered the two-story home of Chris and Lisa McCormack, sidestepping pots and buckets collecting a steady flow of water, and snapping photos with his tablet computer of ceilings marred by brown water stains.